Posted by: nwracing | May 29, 2015

Andromeda Tow Kart Part 3

After my initial success with the rear wishbone fabrication and buoyed with enthusiasm I fabricated the remaining brackets for the front suspension and then fitted them in the jig with the box section which is the main structure at the front of the kart. The picture shows the completely welded brackets. They do overhang the box section underneath and will be strengthened with some 5mm plate. This should be plenty strong enough to take the loads of the front axles.

front suspension mounting brackets

At the front I have decided to use a simple swing axle as it is the easiest to fabricate. I did consider building a four link independent system which would look great however, with all the joints needed to make it all work would have broken my rule on using bits out of my spares bin. I did make a mistake on the front brackets as I added in an extra washer in error for welding only to find that the gap is slightly too wide for the superflex bush. A custom thin spacer will need to be made!

I then focused on the inner rails which go from front to back on the kart and will support the engine plate and tie in the suspension. To get the angles just right took some time and patience with the disc sander and I must have trial fitted each side about six or seven times until they were just right. I suspect that in the past this is where I would have made a mess of it as patience is an absolute requirement. As it turned out each side took about 20 minutes.

Front chassis tubes

My final job was to fishmouth the tubes for the side supports and rear axle.  No amount of DVD watching or talking to experts helps with this process as it does pay to leave them a little long and file them to fit. I think this gets easier with practice.

Rear Chassis Tube

At this point I thought it would be good to consider everything I had learned so far.

  1. Order more tube than you need. You will bend the wrong way or cut too short no matter how careful you are!
  2. Tack things together and leave the finish welding until the end. I did weld the front and rear suspension mounts fully but the rear did distort the tube they are fitted to which will need to be dealt with.
  3. Sequencing the build. My initial idea of how the chassis for the tow kart would come together was quickly thrown out of the window. I mocked up where the tubes were going to go and realised that a number of other things needed to be considered before I could attack the chassis with the welder.
  4. You can never have too many clamps! If there is one thing I wish I had more of it is G-clamps. You never seem to have enough hands to hold on to everything at once.

Next is some more quality time with the welder tacking everything together…

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